Lactic acid Bacteria Isolated from Raw Milk Cheeses: Ribotyping,Antimicrobial Activity against Selected Food Pathogens and Resistance to Common Antibiotics

Abstract

Fermentation with lactic acid bacteria is one of the oldest and effective methods of food preservation that meets the increasing drive of many consumers for foods perceived as minimally processed or free of unwanted chemical preservatives. The isolation and characterization of new wild LAB strains showing potential for application in food preservation may contribute to the processing of food products with good flavor and increasing safety. In the present work ninety-six LAB isolated from raw milk cheeses were subject to a preliminary characterization via identification (ribotyping) and screened for antimicrobial activity against Listeria monocytogenes, Escherichia coli, and Salmonella Newport, while the antibiotic resistance of the isolates against several clinic antibiotics were also studied. Most isolates of interest were identified as Lactobacillus paracasei ss. paracasei, of which, five were shown to completely inhibit Listeria monocytogenes, one inhibited Escherichia coli, five had inhibitory activity against Salmonella Newport, and five were active against both Listeria monocytogenes and Salmonella Newport. The Etest method determined that the isolates were sensitive to β-lactams, including amoxicillin and ampicillin, but were resistant to glycopeptides and aminoglycosides.